配管表面ひずみを用いた管内圧力脈動の測定方法の考察

摘要

配管系で発生する騒音や振動疲労の主要な要因である管内圧力脈動の発生位置や大きさを正確に評価できれば，機器•配管の疲労破損を未然防止するといったプラント保全を効率化できる.現状の技術では結果に曖昧さが残る数値シミュレーションによる予測方法や現地既設圧力計を用いた推定方法に代わる方法として，本研究では，現地の当該箇所の圧力脈動を簡便に直接測定できる非破壊的測定方法を提案した.配管系モックアツプの管内脈動流の測定結果を用いて提案された方法を検証した結果，配管外表面のひずみ測定と厚肉円筒式を用いることにより実用的な精度で圧力脈動の振幅や挙動を測定できることを示した.実験結果を分析することにより提案された方法の精度に影響を与える因子についても考察した.さらに,薄肉円筒式が使用可能な配管寸法の適用範囲についても考察した.%Accurate evaluation of the occurrence location and amplitude of pressure pulsations in piping systems can lead to efficient plant maintenance by preventing fatigue failure of piping and components because the pulsations can be one of the main causes of vibration fatigue and acoustic noise in piping. A non-destructive field method to measure pressure pulsations easily and directly was proposed to replace conventional methods such as prediction using numerical simulations and estimation using locally installed pressure gauges - The proposed method was validated experimentally by measuring pulsating flow in a mock-up piping system. As a result, it was demonstrated that the method to combine strain measurement on the outer surface of pipe with the formula for thick-walled cylinders could measure amplitudes and behavior of the pressure pulsations with a practical accuracy. Factors affecting the measurement accuracy of the proposed method were also discussed.Furthermore,the applicability of the formula for thin-walled cylinders was examined for variously shaped pipes.